Automatic control mechanism for variable speed gear boxes



1 G. w. HAYCOCK AL 2,021,550"

AUTOMATIC'CONTROL MECHANISM FOR VARIABLE SPEED GEAR BOXES 'Filed fict. 1,1934 s Sh'ts-Sheetl r l I I I Nov. 19,1935. s. w. HAYCOCK 51-h.02-l,550,

AUTOMATIC CONTROL MECHANISM'FOR VARIABLE SPEED GEAR BOXES Filed Oqt. 16,1934 SSheets-Sheet 2 PIC-7.1.4

lnverilbrs ear? cool $215356 Nov. 19, 1935 v G. w. HAYcocK ETAL2,021,550

AUTOMATIC cou'rkon MECHANISM FOR VARIABLE SPEED GEAR BOXES Filed' oct,16, 193.4 s Sheets-Sheet 3 W12 J:- fii w 3 Patented Nov. 19, 1935 PATENOFFICE,

raozuso t AUTOMATIC CONTROL MECHANISM FOR VARIABLE: SPEED GEAR BOXESWallace Haycock, Bankhead, Rutherglen and Duncan Campbell, Glasgow,Scotland Appllcaflon October 16, 1934, Serial No. 748,514

" InGreat Britain October 18, 1 933 I r cum; (01.19259) This inventionrelates to a control mam for variable speed gear-boxes, whichisautomatlc in its function of gear changing in so far aenormal forwardrunning conditions are 5 cmcel'ned. "For reversing and emergency dutiesa simple hand control is or may be included.

The principal object of the invention is to provide such a controlmechanism which isactuated automatically in-accordance with the i torquetransmitted by or imposed on the secondary or driven shaftof thegear-box whilst simul- I taneoualy providing. momma with the said ifdesired, a simple means of effe'cting hand control of the gear-box forthe aforementioned. 4

'5 The control mechanism consists essential of a torque governor formedon the secondary shaft of the gear-box and suitablyinterco'nnected witha selector valve or switch. The said se- 20 lactor valve or' switchselectively operates,

through the medium of energized fluid or'elec- 'trical energy, as thecase may be, a series of operatingcylinders or solenoids for eng in thegears of the gear-box; and the arrangement of 25 the aforementionedessential comp'onentsis such that selection of the appropriate. gearratio is automatically obtained bymeans of the torque governor impartingto the selector valve or switch the required displacement proportionate30 to the torque on the secondary shaft of the gear box, that is, in thecase of automotive vehicles the displacement proportionate to the'loador resistance at the driving road wheels. Actual engagement of theselected gear ratio is-proing on the gear operating cylinder or solenoidcorresponding to the displacement of the aforesaid selector valve orswitch. j

A simple and effective means 'otproviding manual control of the gear-boxas an alternate method of changing gearto the automatic functioningdescribed above is by means ofan auxiliary valve or switch operating inconjunction with the automatically displaced valve or switch. 45 Such anauxiliaryvalve or switch is operated by means of a simple hand mechanismandit is arrangedin such a way that'when not in use it permitsunrestrictedoperationof the automatic control mechanism previouslydescribed and 50 when in use it renders such automatic control duced byenergized'fiuid or electrical energy act-- an oil or water pressuresystem; a compressed air system; a vacuum system,which may have itsorigin in the induction pipe of an internal combustion engine, anelectrical generator, battery or accumulator, or a separate pumpor'el'ec- 5 trical generator may be provided forsuchpurpo5e In orderthat neutral position of the gearbox maybe suitably obtained acentrifugal speed governor is provided for preference, on the pri- 10mary or driving shaft of the gear-box lunch a way that it is suitablyinterconnected to the selector valve or switch aforementioned. Suchcentrifugal speed, governor moves the selector valve or switch into itsnormal working position when the driving engine or unit accelerates intoits normal speed range. and returns the" said selector valve or switchto a neutral or inoperative position when the driving engine or unitdecelerates to an'idling speed or stops. 7

A spacing-mechanism, attached to or connected to the selector valve orswitch to prevent the latter from remaining stationary in any positionintermediate between the gear operating positions and a neutral catch,which may be interconnected to the accelerating pedal or control in sucha way that the selector valve may beheld in neutral position to permitfree-wheeling are or may be provided in the control mechanism: and theaforementioned torque govemor' may be formed to constitute a fluidvibration damper in order to minimize the efl'ect of torsionaloscillations on the mechanism. I

"In order that our invention may be properly understood and readilycarried into eil'ect, we havehereunto appended three sheets of drawingsof which:-- v v Figure 1 illustrates a longitudinal sectional view ofthe right hand portion of the general arrangement of a control mechanismsuitable 40 for application to a four-speed (with reverse gear)epicyclic gear-box and designed for fluid operation.

Figure la illustrates the remaining or left hand portion of said generalarrangement of a control mechanism.

Figure 2 is a sectional end view of the torque governor shown in Figure1, taken at theline I-l in the direction indicated by arrow.

'According to our invention and referring to the drawings, A is thedriving shaft of the gearbox and B and C are two adjacent and sectirmsof the driven shaft. D is the, friction clutchior engaging the 4thgear',(top gear' or direct drive) and E, F, G and Hare the brake bandsfor engaging the 3rd, 2nd, 1st (bottom) and reverse gears respectively,as generally arranged in such a train of epicyclic gears. J, K, L. M andN are cylinders for operating the said members D, E, F, G and Hrespectively, and they may be of the plunger type well-known inengineering practice. The actions of the cylinders J, K, L, M and Nreferred to are transmitted to the re- .spective members D, -E, F, G andH by means of suitable lever or link devices and the return ordisengaging strokes of the said cylinders may be accomplished-simply bymeans of a spring device or devices in the manner hereinbeforedescribed. O and P are the two members of a torque governor which arerigidly mounted in -juxtaposition on the respective sections .6 and C ofthe driven shaft of the gear-box and which are interconnected by meansof springs Q in such a manner that the torque imposed on the drivenshaft is transmitted between the aforementioned members 0 and P throughthe medium of the said springs Q, thus producing in the latter a strainand between the said members 0 and P a consequent relative rotationalmovement proportional to such torque. The springs Q, previously referredto, are carried between, or mounted on, the webs R and S which arearranged alternately and which are formed in the torque governor members0 and P respectively. In order to safeguard the mechanism againstover-straining, whilst simultaneously allowing the flexibility requiredfor satisfactory operation,

the said members 0 and P are also provided with stop pieces T and Urespectively, which are disposed in such a manner that the relativerota-.

pended. The said bevel pinions V engage suitable teeth Y formed in theother torque governor member P in such a manner that the relativerotational movement of the aforementioned members 0 and P of the torquegovernor. causes a corresponding rotation of the pinions V and W abouttheir spindles X. A sleeve Z, which can slide axially on the extendedportion A of the member 0, carries arms 3, such arms projecting throughsuitable apertures C in the membersO and P and having teeth D formed inthem to engage with the aforementioned spurpinions W, in the manner of arack and pinion 'mechanism, so that rotation of the said spur pinions Wabout their spindles X causes the sleeve Z to moveaxially, the extent ofsuch movement or displacement being therefore proportional to thetorque, transmitted by or imposed on the driven shaft B and C of thegear-box. A collar E is mounted, by means of a ball-bearing F on thesaid sliding sleeveZ in such a manner that it is non-rotational and isconnected by pins G to a lever H which has its fulcrum J on the'gearboxcasting or other convenient member. The compartments of the torquegovernor, formed between the aforementioned members 0 and P for thepurpose of accommodating the springs Q in the manner hereinbeforedescribed are designed in such a way that they may be packed with greaseor other suitable substance thus causing the webs R and S, previouslyreferred to, to function as plungers and giving to the torque governoran action similar to that of a dashpot or damper. Such damping action ofthe aforementioned torque governor minimizes the effect of torsionalvibrations and momentary fluctuations of torque transmitted on thecontrol mechanism. 4

A centrifugal speed governor, of a type wellknown in engineeringpractice, is shown in Figure i of the accompanying drawings as mountedon the driving shaft A of the gear-box. Such governor consistsessentially of, for preference, two balls or weights K each mounted on abellcrank lever L which is carried by the member M rigidly fixed to thedriving shaft A. The said bell-crank levers L act in slots N formed in arotating but axially displaceable sleeve or member 0 in such a mannerthat outward move ment of the aforementioned ballsK under centrifugalforce produces axial displacement of the sleeve 0 against the action ofthe helical spring P which is" interposed between the said member M andsleeve 0 A collar Q is mounted, by means of a ball-bearing B on theaforedescribed sleeve 0 in such a manner that it is non-rotational andis connected by means of pins S to a-lever T such pins S constituting afulcrum for the said lever T, which is movable in accordance with theaction of the centrifugal speed governor. A link U interconnects thelever H from the torque governor as hereinbefore described and the leverT from the centrifugal speed governor at the pivot pins V and Wrespectively, and the said lever T is conneeted at its extremity to acrosshead X by means of a pin Y the arrangement being such that theposition of, or displacement given to, the crosshead X referred tovaries with the individual or combined actions of theaforedescribedtorque governor and centrifugal speed governor. Thecrosshead X, as above, is carried by a slide bar or member Z of a guidepiece A in such a manner that it is capable of sliding along the same,the extent of such sliding movement being, however, suitably restrictedby means of springs B". The guide piece A is connected by means of aspindle C to a selector valve D and the outer end of such spindle C issupported in a guide E conveniently formed in the gear-box casting. i

The selector valve D referred to above has a number of ports F, G, H,and J, which correspond with the number of operating cylinders J, K, Land M respectively for the forward running gears, and a series ofannular spaces K, L, and

M arranged between the said ports for the outflow of discharged fluid.The said selector valve D slides, under the actuation of theaforementioned spindle C, inside a valve chest N which is formedintegrally with the gear-box casting and which has a number of ports 0',P, Q, R, and S, respectively connected by means of pipes, T, U, V. W.and}? to the gear operating cylinders J, K, L, M and N. An auxiliaryvalve Y", which is hand-operated by means of a simple control (not shownin the accompanying drawings) is'actuated by means of the spindle Zpassing through the stuffing-box A formed in the valve chest N" andslides inside the said valve chest N and selector valve D. Suchauxiliary valve Y has ports B C D and E which are in its normal orinoperative position, they are directly opposite to the ports P", Q andB respectively of the aforementioned valve chest N and ports F and Clarranged adjacent to the ports R, and S ofthe said valvechest. Annularspaces H, J, K L M, and N arrangedfor the outflow of discharged fluid,are also formed between the ports of the auxiliary valveY, and theinterstices 0 P and Q formed between the valve chest N selector valveDand said auxiliary valve Y also constitute outlets for-dischargedfluid. Inorder that fluid discharged from the gear operating cylinders.shall notbe entrained in any of the interstices of the valve mechanismhereinbefore described but shall have an unrestricted flow to the sump,situated for convenience in the-bottom of the gear-box casting, theaforementioned annular spaces EH3, J K, L and M of the auxiliary valveY" are interconnected by a longitudinal groove or channel R the fluidfrom which passes through a hole S in the selector valve 1) and thencethrough a longitudinal slot T in the valve chest N to the sumpreferred'to. The said groove R hole S and slot '1', which areindicated'in dotted lines inFigure 1 of the accompanying drawings, arein line. with each other and are 'preferablyat a positioncircumferentiaily remote from the ports of the selector and auxiliaryvalves D and Y respectively. In order to give the required operatingpositions of the selector valve D previously described a valve spacingmechanism, comprising a suitably notched plate U secured to theaforementioned guide piece A and against'which bears a roller Vloaded-by a spring W and carried by' the member X attached to thegearbox casting, is provided, and the arrangement of the same is suchthat when the above mentioned roller V is bearing in the notch Y of thenotched plate U? the selector valve D is in a position to the lei'tofthat indicated in the drawings (Figure 1.) whereby the ports F", G4, H,and J are closed to the pressure fluid'by the auxiliary valve Y (in itsnormal position) and are also closed by the'valve chest N When the saidroller V is in the notch Z of the notched plate U the port I" of theselector valve D coincides with the port 0 of the valvechest N Figure 1of .the accompanying drawings indicates the control mechanism in such aposition, Similarly when the roller V as above is respectively in thenotches A, B and C the corresponding positions of the said selectorvalve D are such that the ports (3 and P of the selector valve D andvalve chest N respectively coincide, ports H and Q coincide, and ports Jand R coincide. The pressure fluid enters the valve chest N from asuitable connection (not shown) secured at Dtand passes to the interiorof the aforementioned selector valve D and auxiliary valve Y? throughapertures E4 in the outer end of the former. In order to eliminatehydraulic end thrust fromthe said auxiliary valve Y similar apertures Fare formed in the outer end of the same, which allow the pressure fluidto fill the chamber G of the valve chest N. Feather pieces or webs H areformed in, or attached to, the valve chest N in such a manner that,being accommodatedby suitable slots in the cuter ends of theaforementioned selector valve D and auxiliary valve Y they prevent theselatter from rotating and thus maintain the ports of the said valves andvalve chest in proper alignment.

A neutral catch J is also incorporated in the der P control mechanismfor the purposes of allowing free-engine running (1. e. the rotation ofthe driving shaft A without engagement of any gea'rs) and free-wheelingof the vehicle or driven unit, in the manner hereinafter described. The8 said neutral catch J isarranged to engage with a suitable notch Kformed in the aforementioned notched plate U, such engagement occurringwhen'the roller V is in the notch Y and the selector valve D is in itsneutral position, or 10 position of no gear engagement, as hereinbeforedescribed- A spindle L, which is journalled in the part M formed in thegear-box casting, car ries the said neutral catch J and a lever Nin' themanner of a bell-crank lever, the lever'N' being connectedto a rod 0which enters a cylin- A washer Q attached to the end of theaforementionedxrod 0 and. contained in the cylinder P constrains ahelical spring R between lt'self and the end of the saidcylinder P :0and a rod S which is connected to the accelerator pedal or mechanism ofthe driving engine or unit, carriesa friction, plunger. T also containedinside the said cylinder P The arrangement of the foregoing is suchthat, when the accelerator pedal is released for stopping, slowing orfreewheeling, the consequent pulling action of the rod S through themedium ofv the frictional resistance between the plunger Ti, and thecylinder P causes compression in the spring R which is sufficient toenable the neutral catch J to engage the notch K, previously referredto, whenever the selector valve D attains its neutral position.

This neutral position of the selector valve D is maintained until suchtime as the accelerator 3 pedal is depressed, when, due-to the reversemotion of the aforementioned rodS acting through the said frictionalmedium, the neutral catch .1 is disengaged and the selector valve D thusbecomes free to assume its appropriate working w position. I v

The action of the aforedescribed control mechanism, underitsvariousworking conditions and as applied, for example, toautomobiles, is as follows:- When the engine and the driving shaft, Aare at rest the balls K of the centrifugal speed 80vernor are in theposition indicated by dotted lines at 22 in Figure 1 of the accompanyingdrawings, and, there being no torque imposed on the torque governor, theconfiguration of. the said torque governor, lever and link U are asshown in the above-mentioned Figure 1. Therefore the position of thelever T from the centrifugal speed governor is as indicatedby thecentreline 3- 3 and the roller V previously described is in notch Y ofthe notched plate U, i. e. the selector valve D is in its neutralposition. Under these circumstances the neutral catch .J is, ashereinbefore explained, in engagement with the notch K and'when theengine is started it may be run free of thetransmissionto-arrv speed bymeans of the hand throttle-control, theeifect of the centrifugal speedgovernor beingsimply to strainthe springs, B Whenever the acceleratorpedal is depressed,- however, the said, neutral catch J is disengagedand underthe action of'the said springs B the resistance of the roller Vis overcome to a sufficient extent to allow the selector valve D to moveinto its operating position, 7 whereby, the notch Z becomes engaged bythe aforementioned roller V and the ports F and O, of the selector valveD and valve chest N" respectively coincide and allow the access ofpressure fluid to the operating cylinder J of the 4th ortopastofgears."'ihesngagementoi'thisset of gears'oausesa riseinen'gine torque, which,acting'throughthetorquegovernorintheaforedescribed manner additionalstrain mthespringsB'sufflciIattoiauIether-esistance come, when theselector valve D toengagethetrdsetofgearaLaJhemteha enga'gesthesaidrolle'rVhportsG'andP'coinoide and the pressure fluid, operates thecorresponding cylindq' K. Simultaneously with the cuttin of the'said 3rdsat of gearsthe aforesaid4thsetofgearsisdisengaged,slneethefluidinthecylinderJisfree todischarge,throughtheportO'ofthevalvechestN,theintersticeO andthealot'linthevalvechestNJothesi-ip ating cylinder L; and for 1stgear'the notch CM,

is constrained-to engage with the roller W and the ports J and ll.coincide allowing access of the pressure fluid to the cylinder M.Thereafter the action of the control mechanism during normal forwardrunning is simply that when the torque in the driven shaft B and 0increases to such an extent as to be outside the designed range of theoperating set of gears the springs H of the guide piece A are strainedby the torque governor and interconnecting mechanism as hereinbeforedescribed to a degree whereby the resistance of the roller V to theengaged notch ofthe notched plate U is overcome and the selector valveD' moves to the adjacent position for engaging the next and lower set ofgears in the manner previously shown, and conversely, when the torquetransmitted by the said driven shaft A and B decreases beyond thedesigned range of the set of gears in operation, the selector valvesimilarly effects engagement of the adiacent and higher set of gears. Toobtain freewheeling effect the accelerator pedal is released and theengine and driving shaft A slow down, thus causing the vehicle toover-run the engine, and producing a momentary reversal of torque in thedriven shaft A and B and a consequent reversal of the action of thetorque governor, which latter constrains the lever T from thecentrifugal speed governor to the position indicated by the centre lineH in Figure l of the accompanyingdrawingsiftheengineisrunningwithinitsworkingspeed range; or to theposition indicated by the centre line Hit the engine is idling orstopped. In any case, however. the strain imposed on the springs Bcausesathe selector valve D' to move to its neutral position and, theneutral catch J engaging with the notch K in the manner previouslydescribed, to be retained in such position until the accelerator pedalis again depressed. l'or reverse gear operation the aforedescribedauxiliary valve Y is moved by means of the simple hand controlpreviously referred to to ocoupy a position whereby the port 0- of thesaid auxiliary 'valve coincides with the port S of the valve chest Nthus permitting the access of pressure fluid to the operating cylinderN; and in order to use the engine for braking purposes the auxiliaryvalve Y is moved until the ports I" and R of the said auxiliary valve Yand valve chest N respectively coincide, when the pressure fluidsimilarly operates the cylinder ll, thus engaging I the 1st set ofgears. Since the operations of rev'eraing and braking by means of theengine, as described above, entail a reversal of torque in the drivenshaft A and B and in the torque governor, and since the torquemagnifications of the sets I of g used for such purposes are generallyof a high rder, the stop pieces T and U, which, as aforedescrihed, areincorporated in the said torque governorare necessary in order tosafeguard the mechanism in general by limiting the strain im- 1 posed onthe springs B of the guide piece A. As will be seen from theaccompanying drawings,

it is impossible for two sets of gears to be in simultaneous engagementand, whatever operation ties place in the mechanism, the fluid from'the:0 cylinders of thedisengaged sets of gears is'slways free to drain tothe sump in the manner hereinbeforedescribed.

Having now particularly described and ascertained the nature of our saidinvention and infLS what manner the same is to be performed,we declarethat what we claim is:-

l. Automatic control mechanism for variablespeed gear-boxes, comprisinga torque governor,

a driven shaft for the gear-box having two co- 89 axial sections, suchtorque governor consisting essentially of two juxtaposed members, eachof which is rigidly secured to a section of the aforesaiddriven shaft;yielding means for interconnecting the said governor members in such a33 manner that the torque transmitted by the driven shaft issimultaneously transmitted between the said members, causing a strain inthe yielding means and a consequent relative rotational movement betweenthe said members proportional 40 in extent to the torque transmitted; asliding sleeve mounted on one of the aforesaid members; gearingconnected to the said sliding sleeve and interconnecting the saidmembers whereby the relative rotation of the latter imparts aproportionate axial displacement to the aforesaid sliding sleeve; and aselector valve which operates inside a valve body and interconnected tothe aforesaid sliding sleeve of the torque governor in such a way thatit is actuated in accordance with the relative rotational movement ofthe members of the torque governor, the said selector valve having aseries 'of ports for the guidance of energined fluid and the said valvebody having a series of similar ports connected to a correspondingseries of fluid pressure cylinders for engaging the gears of'thegear-box in a manner whereby the gear of speed ratio appropriate to thetorque transmitted is engasedon account of the operation by energizedfluid of the corresponding fluid pressure cylinder.

2. Automatic control mechanism for variable speed gear-boxes, as inclaim 1, characterized in the provision of a centrifugal speed governorwhich is mounted on, and rotates with, the driving shaft of the gear-boxwhich rotates at a speed directly proportional to the speed of thedriving engine or unit and is interconnected to the aforedescrihedtorque governor and selector valve in such a way that, as the drivingengine or unit accelerates to its normal working speed range the saidcentrifugal speed governor moves the selector valve into its operatingposition and conversely, as the driving engine or unit decelerates to anidling speed or stops the centrifugal speed governor moves the selectorvalve to its neutral or inoperative position.

3. Automatic control mechanism for variable speed gear-boxes, as inclaim 1, characterized in the provision of an auxiliary valve which'maybe hand operated throughthe medium of any suitable device and which hasfor its object the engagement of reverse gear, and of a forward set orsets of gears for engine breaking and emergency functions; the saidauxiliary valve being arranged to operate in conjunction with theaforementioned selector valve and valve body and having a series ofports disposed in such a way that, by suitably moving the auxiliaryvalve, the said series of ports permits the required flow of energizedfluid to and from the aforementioned fluid pressure cylinders in orderto engage reverse gear, lst forward gear and whichever set of gears maybe required for such like purpose; and the said auxiliary valve beingarranged in such a manner that, when in use, it renders theaforementioned selector valve inoperative, but conversely, when not inuse, it does not obstruct the normal action of the said selector valve.

4. Automatic control mechanism for variable speed gear-boxes, as inclaim 1, characterized in the provision of a spacing mechanism, which isconnected to the aforementioned selector valve in such a manner that thesaid selector valve moves instantaneously from one operating position tothe adjacent operating position under the individual or combined actionsof the torque governor and centrifugal speed governor aforementioned.

5. Automatic control mechanism for variable speed gear-boxes, as inclaim 1, characterized in the provision of a neutral catch which has forits object the permitting of running of the driving engine free of powertransmission, and also of free-wheel effect, and which is connected tothe accelerator pedal or mechanism in such a manner that when the saidaccelerator pedal is released for slowing orstopping the driving enginethe said neutral catch is constrained to engage a suitable notch formedin the aforementioned selector valve whenever the said selector valveattains its neutral position and position of no gear engagement; andconversely, when the accelerator pedal is depressed for engineacceleration the said neutral catch is rendered free of such engagingnotch, thus enabling the aforesaid selector valve to move to its normalwork ing position.

6. Automatic control mechanism for variable speed gear boxes, as inclaim 1, characterized in so forming the juxtaposed members of thetorque governor that, when grease or other suitable substance iscontained between them, they function in the manner of a dashpot orvibration damper and relieve the said control mechanism from the efiectof torsional vibrations and momentary fluctuations in torque.

7. Automatic control mechanism for variable speed gear-boxes, as inclaim '1, characterized in so forming the juxtaposed members of thetorque governor that relative rotational movement between them ;isrestricted to suitable limits, having regard to both directions oftorque application, in order to safeguard the said control mechanismagainst overstrain.

GEORGE WALLACE HAYCOCK. DUNCAN CAMPBELL.

